JP2018100363A - Conductive adhesive sheet and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive adhesive sheet that is excellent in prevention of excessive curling and followability to a surface shape of an adherend, without impairing excellent conductivity or surface insulation.SOLUTION: A conductive adhesive sheet has a conductive base material. At one side of the conductive base material, directly provided is a resin layer with a surface resistance value of 1.0×10Ω or more. At the other side of the conductive base material, provided is a conductive adhesive layer.SELECTED DRAWING: None

Description

  The present invention relates to a conductive adhesive sheet.

  Conductive adhesive sheet is used for shielding unnecessary electromagnetic waves radiated from electric and electronic devices, shielding harmful electromagnetic waves generated from electric and electronic devices, and grounding for antistatic charging, etc. It is used for.

  Moreover, in recent years, image display devices possessed by terminals such as smartphones and personal computers can prevent light leakage from a backlight or the like in order to maintain good visibility as a new added value, and have an earth function. What you have is needed. In connection with it, in addition to favorable electroconductivity, as a conductive adhesive sheet used for those manufacture, favorable insulation is calculated | required.

  As a conductive pressure-sensitive adhesive sheet that has both light shielding properties, conductivity and insulation properties, a conductive pressure-sensitive adhesive layer is laminated on one side of a base substrate having a structure in which the same kind of metal layer is formed on both sides of a resin film, A conductive pressure-sensitive adhesive sheet in which a light-shielding insulating layer is laminated on the other surface of a base substrate is known. (See Patent Document 1).

  The conductive pressure-sensitive adhesive sheet described in Patent Document 1 uses a base film made by laminating the same kind of soft aluminum foil on both sides of a polyester film with an adhesive. However, since it is difficult to appropriately control the tension of the base substrate, the conductive adhesive sheet obtained by using the base substrate easily curls when sticking to the adherend or removing the release sheet. As a result, there were cases where the workability of sticking and the followability of the conductive adhesive sheet to the adherend were lowered.

JP 2014-058108 A

  The problem to be solved by the present invention is to provide a conductive pressure-sensitive adhesive sheet that is excellent in curling prevention and adherence to an adherend without impairing good electrical conductivity and surface insulation.

The inventors have a resin layer having a surface resistance value of 1.0 × 10 ⁸ Ω or more directly on one surface of the conductive substrate, and the other surface side of the conductive substrate. It has been found that the above-mentioned problems can be solved by having a conductive pressure-sensitive adhesive layer.

  The conductive thin pressure-sensitive adhesive sheet of the present invention is a simple process in which a resin layer having a surface resistance value of a certain value or more is directly provided on one surface of a conductive substrate, and has good conductivity, light shielding properties, and surface resistance. Since the curling prevention and the followability to the adherend are excellent without impairing the insulating properties, the pasting workability can be remarkably improved.

The conductive pressure-sensitive adhesive sheet of the present invention has a resin layer having a surface resistance value of 1.0 × 10 ⁸ Ω or more directly on one surface of the conductive substrate, and the other side of the conductive substrate. It has a conductive adhesive layer on the surface side.

  Below, the electroconductive adhesive sheet of this invention is demonstrated in more detail based on the component. The “sheet” in the present invention means a form in which an adhesive layer formed using at least one conductive adhesive is provided on a conductive substrate or a release sheet. All forms of products such as rolls, thin plates, strips (sheets) and the like are included.

(Resin layer)
As the resin layer in the conductive adhesive sheet of the present invention, a resin layer having a surface resistance value of 1.0 × 10 ⁸ Ω or more is used. Thereby, the insulation of the surface of the said resin layer can be improved. The surface resistance value of the resin layer is more preferably 1.0 × 10 ¹⁰ Ω or more, and 1.0 × 10 ¹² Ω to 1.0 × 10 ¹⁶ Ω further improves the insulation. This is particularly preferable.

  The resin layer is provided directly on one surface of the conductive substrate. Thereby, the effect of further improving curling suppression and followability to the adherend can be obtained.

  The resin layer can be formed by directly coating the resin composition for forming the resin layer on one surface of the conductive base material and drying it.

  As the resin composition, for example, a resin composition containing polyurethane resin, polyester resin, polyamide resin, acrylic resin, nitrocellulose, or the like can be used. Among them, it is preferable to use a resin composition containing a polyurethane resin in order to further improve the adhesion to the conductive substrate, and it is particularly preferable to use a resin composition containing a polyester urethane resin. preferable.

  As said polyester urethane resin, it is preferable to use what a glass transition temperature is -30 degreeC-30 degreeC, It is more preferable to use what is -20 degreeC-30 degreeC, -15 degreeC-25 degreeC It is more preferable to use what is and it is especially preferable to use what is -10 degreeC-25 degreeC. When the glass transition temperature of the polyester urethane resin is within this range, the resin layer has suitable flexibility and hardness. Therefore, when a specific bent shape is given to the conductive pressure-sensitive adhesive sheet of the present invention, the resin layer cracks. The occurrence of chichire due to occurrence is particularly difficult.

  The glass transition temperature of the polyester urethane resin is defined as the glass transition temperature, which is the tan δ peak temperature of the dynamic viscoelastic spectrum at a frequency of 1 Hz measured as follows.

  Polyester urethane resin is formed to a thickness of 50 μm with a bar coater. Next, a test piece (sample length 20 mm, film thickness 50 μm) cut to a sample length of 20 mm was -150 ° C. to 250 ° C. using a viscoelasticity tester at a frequency of 1 Hz and a temperature rising time of 3 ° C./1 min. The storage elastic modulus (G ′) and the loss elastic modulus (G ″) are measured until the loss tangent tan δ is calculated from the following equation.

Loss tangent tan δ = G ″ / G ′
Examples of the viscoelasticity tester include DMS210, DMS220, and DMS6100 manufactured by Seiko Instruments Inc.

  As the resin layer, it is preferable to use a resin layer containing a curing agent for imparting durability at high temperatures. As the curing agent, an aliphatic or alicyclic isocyanate curing agent is preferably used.

  As the resin layer, it is possible to use a resin layer in which the polyester urethane resin having a glass transition temperature of −30 ° C. to 30 ° C. and an aliphatic or alicyclic isocyanate forming a relatively flexible crosslinked structure are crosslinked. Since it is easy to obtain a suitable elastic modulus, when a specific bent shape is given to the conductive pressure-sensitive adhesive sheet of the present invention, the resin layer is hardly cracked, and it becomes easy to stably obtain the insulating property of the conductive pressure-sensitive adhesive sheet. preferable.

  Examples of the aliphatic or alicyclic isocyanate include hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, trimethylhexamethylene isocyanate, 1,6,11-undecane triisocyanate, lysine diisocyanate, lysine ester triisocyanate, 1,8-diisocyanate-4. -Isocyanatomethyloctane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate are used. Further, trimers of these isocyanates can be preferably used, and among them, diisocyanate adducts, biurets, and nurates are preferable. Among these, hexamethylene diisocyanate or isophorone diisocyanate adduct, biuret, or nurate is preferable because the elastic modulus is easily controlled, and biuret or nurate is particularly preferable. A hardening | curing agent may be used independently and may use 2 or more types.

(Conductive substrate)
A metal base material is mentioned as an electroconductive base material used for manufacture of the electroconductive adhesive sheet of this invention.

  As the metal substrate, for example, a substrate made of gold, silver, copper, aluminum, nickel, iron, tin or an alloy thereof can be used, and a substrate made of aluminum or copper can be used. Since it is excellent in the shape followability of an electroconductive base material, it is preferable.

  Examples of the base material made of aluminum include an aluminum foil (thickness: 30 μm) manufactured by Sumi Light Aluminum Foil Co., Ltd. Examples of the material of the aluminum foil include 1N30 and 8079.

  As the base material made of aluminum, it is preferable to use a soft material (O material) because it is flexible and the conductive adhesive sheet easily follows the shape of the member.

  Moreover, as the base material made of copper, for example, a base material made of electrolytic copper, a base material made of rolled copper, or the like can be used.

  As the base material made of electrolytic copper, electrolytic copper foil (thickness 30 μm) manufactured by Fukuda Metal Foil Powder Co., Ltd. can be used.

  As the rolled copper foil, a T-rolled copper foil (thickness 30 μm) manufactured by Nippon Foil Co., Ltd. can be used.

  As the conductive substrate, the thickness is preferably 3 μm to 50 μm, more preferably 4 μm to 40 μm, and it is preferable to use a metal foil or the like having a thickness of 5 μm to 30 μm. Is preferable because it can easily follow the shape of the member and curl can be suppressed.

(Conductive adhesive layer)
The conductive pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer formed using a pressure-sensitive adhesive composition containing conductive particles and a pressure-sensitive adhesive component. As the pressure-sensitive adhesive component, for example, pressure-sensitive adhesive compositions such as acrylic pressure-sensitive adhesive compositions, silicone-based pressure-sensitive adhesive compositions, and rubber-based pressure-sensitive adhesive compositions can be used. It is preferable to use an acrylic pressure-sensitive adhesive composition that can be maintained over a wide range.

  As the acrylic pressure-sensitive adhesive composition, for example, a composition containing an acrylic copolymer can be used. As said acrylic copolymer, what is obtained by polymerizing a monomer component can be used.

  As said monomer, a C1-C14 (meth) acrylate monomer can be used preferably. Examples of the (meth) acrylate having 1 to 14 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n -Hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, cyclohexyl (meth) acrylate, monomers such as 2-ethylhexyl (meth) acrylate, and the like 1 type (s) or 2 or more types are used. Among these, as the (meth) acrylate having 1 to 14 carbon atoms, it is preferable to use a (meth) acrylate having 4 to 12 carbon atoms in the alkyl group, and a linear or branched structure having 4 to 9 carbon atoms. It is more preferable to use (meth) acrylate having, and it is particularly preferable to use n-butyl acrylate and 2-ethylhexyl acrylate alone or in combination.

  The (meth) acrylate having 1 to 14 carbon atoms is preferably used in the range of 80 to 98.5 parts by mass, and in the range of 90 to 98.5 parts by mass with respect to the total amount of the monomer components. More preferably.

  As the monomer component, it is preferable to use a highly polar vinyl monomer. As said highly polar vinyl monomer, the vinyl monomer which has a carboxyl group, the vinyl monomer which has a hydroxyl group, the vinyl monomer which has an amide group, etc. can be used individually or in combination of 2 or more types. Among these, as the high-polarity vinyl monomer, it is preferable to use a monomer having a carboxyl group because the adhesiveness of the conductive pressure-sensitive adhesive layer can be easily adjusted within a suitable range.

  As vinyl monomers having a carboxyl group, acrylic acid, methacrylic acid, itaconic acid, maleic acid, (meth) acrylic acid dimer, crotonic acid, ethylene oxide-modified succinic acid acrylate, etc. can be used, among which acrylic acid Or it is preferable to use methacrylic acid as a copolymerization component, and it is especially preferable to use acrylic acid.

  It is preferable that content of the vinyl monomer which has a carboxyl group is 1-10 mass parts with respect to the whole quantity of the said monomer component, It is preferable that it is 1.5-6 mass parts, 2-4 It is preferable that it is a mass part. By being the said range, it is easy to adjust the initial adhesiveness to a metal and the adhesiveness after high-temperature, high-humidity storage to a suitable range. In particular, when acrylic acid is used, the acrylic acid content is required to be 1 to 6 parts by mass in the monomer component constituting the acrylic copolymer for stable conductivity over time. It is preferable for imparting excellent adhesiveness.

  Examples of the monomer having a hydroxyl group include hydroxyl groups such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate. Containing (meth) acrylates can be used.

  Examples of the monomer having an amide group include N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylamide, and N, N-dimethylacrylamide.

  Other highly polar vinyl monomers include vinyl acetate, ethylene oxide-modified succinic acid acrylate, sulfonic acid group-containing monomers such as 2-acrylamido-2-methylpropane sulfonic acid, 2-methoxyethyl (meth) acrylate, 2 -Terminal alkoxy modified (meth) acrylates such as phenoxyethyl (meth) acrylate.

  The content of the other highly polar vinyl monomer is preferably 0.2 to 15 parts by mass, and 0.4 to 10 parts by mass with respect to the total mass of the other highly polar vinyl monomers. Is more preferable, and 0.5 to 6 parts by mass is particularly preferable because it is easy to adjust the adhesiveness of the pressure-sensitive adhesive within a suitable range.

  The acrylic copolymer can be obtained by copolymerizing the monomer components by a known method such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, or an emulsion polymerization method.

  The weight average molecular weight of the acrylic copolymer is preferably 300,000 to 1,500,000, more preferably 500,000 to 1,200,000 when forming a conductive pressure-sensitive adhesive layer capable of maintaining excellent conductivity over a long period of time. .

  As said adhesive composition, when forming the electroconductive adhesive layer provided with the much more excellent adhesive force, what contains tackifying resin can be used. Examples of the tackifying resin include rosin resins, terpene resins, aliphatic (C5) and aromatic (C9) petroleum resins, styrene resins, phenol resins, xylene resins, methacrylic resins, and the like. Can be mentioned. Among these, a rosin resin is preferable, and a polymerized rosin resin is particularly preferable. It is preferable to use tackifying resin in the range of 10-50 mass parts with respect to 100 mass parts (solid content) of a (meth) acrylic-type copolymer.

  As the conductive adhesive layer, those containing various additives can be used as necessary. Examples of the additive include a plasticizer, a softener, a metal deactivator, an antioxidant, a pigment, and a dye.

  The conductive pressure-sensitive adhesive layer contains an antioxidant from the viewpoint of suppressing chelate cross-linking of the acrylic copolymer by metal ions derived from metal foil or metal particles and imparting stable adhesiveness over time. It is preferable to use one. Examples of the antioxidant include benzotriazole, tolyltriazole and its potassium salt, 3- (N-salicyloyl) amino-1,2,4 triazole, 2- (2'-hydroxy-5methylphenyl) benzotriazole and the like. Of these, benzotriazole is preferable because of its high solubility and the effect of preventing reduction in adhesive strength.

  Although it does not specifically limit as content of a triazole type compound, 0.05-3.0 mass parts is preferable with respect to 100 mass parts (solid content) of an acrylic adhesive composition. Among these, 0.1 to 1.5 parts by mass is preferable, and 0.3 to 1.0 part by mass is most preferable. By setting it as the said content, it becomes easy to obtain especially suitable holding power, and it becomes easy to suppress especially the adhesive force fall after a high temperature, high humidity environment test.

  As the pressure-sensitive adhesive composition, it is possible to form a conductive pressure-sensitive adhesive layer in which a three-dimensional crosslinked structure is formed by using a composition containing a crosslinking agent, and as a result, the cohesive force can be improved. Examples of the crosslinking agent include known crosslinking agents such as isocyanate crosslinking agents, epoxy crosslinking agents, chelate crosslinking agents, and aziridine crosslinking agents. The type of the crosslinking agent is preferably selected according to the functional group of the monomer component described above.

  The addition amount of the crosslinking agent is preferably used in the range where the gel fraction of the obtained conductive pressure-sensitive adhesive layer is 25 to 65 parts by mass, more preferably 35 to 60 parts by mass, and most preferably 40 to 55 parts by mass. In order to maintain excellent conductivity, it is important that the conductive adhesive sheet and the adherend are in close contact with each other without causing floating. The conductive pressure-sensitive adhesive sheet having a conductive pressure-sensitive adhesive layer with a gel fraction in the above range has excellent adhesive strength that hardly causes peeling over time, and therefore can exhibit excellent conductivity and can maintain it for a long period of time. .

  The gel fraction is calculated by the following formula.

  Gel fraction (parts by mass) = {(Adhesive mass after being immersed in toluene) / (Adhesive mass before being immersed in toluene)} × 100

(Conductive particles)
As the conductive particles contained in the conductive adhesive layer, metal powder particles such as gold, silver, copper, nickel, and aluminum, carbon such as acidic carbon, conductive resin particles such as graphite, solid glass beads, hollow A glass bead having a metal coating on the surface can be used. Among these, it is preferable to use nickel powder particles, copper powder particles, or silver powder particles because of excellent conductivity, adhesiveness, and productivity. More preferred are surface needle-shaped nickel particles having a large number of needle-like shapes on the surface of the particles produced by the carbonyl method, those obtained by smoothing the surface needle-shaped particles into spherical particles, Examples thereof include copper powder and silver powder produced by a high-pressure swirling water atomization method. Two or more kinds of these conductive particles may be mixed and used.

  The shape of the conductive particles is preferably a spherical shape or a surface needle shape. The aspect ratio is not particularly limited, but is preferably 1 to 2, more preferably 1 to 1.5, and most preferably 1 to 1.2. The aspect ratio can be measured with a scanning electron microscope.

The tap density of the conductive particles is not particularly limited, but 2 to 7 g / cm ³ is preferable because it does not easily settle or aggregate during production. More preferably from 3 to 6 g / cm ^3, and most preferably 4-5 g / cm ^3.

  Although it does not specifically limit as a particle diameter of electroconductive particle, It is preferable that particle diameter d50 is 3-20 micrometers and particle diameter d85 is 6-40 micrometers. d50 is more preferably 4 to 15 μm, still more preferably 5 to 12 μm, and most preferably 6 to 10 μm. D85 is more preferably 8 to 30 μm, still more preferably 9 to 25 μm, and most preferably 10 to 20 μm. In addition, when mixing 2 or more types of electroconductive particle, it is preferable that the particle diameters d50 and d85 after mixing are the said ranges.

  The particle diameter d50 is a 50% cumulative value (median diameter) in the particle size distribution. The particle diameter d85 is an 85% cumulative value. These particle sizes are values measured by a laser analysis / scattering method. Examples of the measuring device include Nikkiso Microtrack MT3000II, Shimadzu Laser Diffraction Particle Size Distribution Analyzer SALD-3000, and the like.

  The particle diameter d50 of the conductive particles is preferably 50 to 150% of the thickness of the conductive pressure-sensitive adhesive layer, and d85 is preferably 80 to 200%. By using the conductive particles in the above range, it is easy to achieve both conductivity and adhesiveness. d50 is more preferably 60 to 120%, and most preferably 70 to 100%. d85 is more preferably 100 to 150%, and more preferably 110 to 140%.

  The content of the conductive particles in the conductive pressure-sensitive adhesive layer is not particularly limited as long as the content of the conductive particles in the conductive pressure-sensitive adhesive layer is the above content, but the acrylic pressure-sensitive adhesive composition 5-100 mass parts is preferable with respect to 100 mass parts (solid content) of a thing, More preferably, it is 10-100 mass parts, More preferably, it is 20-80 mass parts. By making content of electroconductive particle into the said range, it becomes easy to make electroconductivity and adhesiveness compatible.

  As a method for producing the pressure-sensitive adhesive composition containing the conductive particles, for example, when an acrylic pressure-sensitive adhesive composition is used, an acrylic copolymer, conductive particles, and a solvent or additive as necessary. Etc. may be dispersed with a dispersion stirrer. Examples of the commercially available dispersion stirrer include a dissolver manufactured by Inoue Seisakusho, a butterfly mixer, a BDM biaxial mixer, and a planetary mixer. Among them, a dissolver or a butterfly mixer that can apply a medium share with little viscosity increase of the pressure-sensitive adhesive composition during stirring is preferable.

  Although it does not specifically limit as solid content of the adhesive composition containing the said electroconductive particle, 10-70 mass parts is preferable, More preferably, it is 30-55 mass parts, Most preferably, it is 43-50 masses. Part.

  As a preferable configuration of the conductive thin adhesive sheet of the present invention, the one-sided conductive adhesive sheet having a conductive adhesive layer only on the other surface side of the conductive substrate, or one of the conductive substrates. Directly on the surface, having the resin layer, on the surface of the resin layer, having a conductive adhesive layer directly or via the colored layer, and conductive on the other surface side of the conductive substrate Examples thereof include a double-sided conductive pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer.

  The total thickness of the conductive pressure-sensitive adhesive sheet is preferably 100 μm or less, more preferably 80 μm or less, and particularly preferably 60 μm or less. By being in the said range, it becomes easy to follow the shape of various members, ensuring adhesiveness and electroconductivity. The total thickness of the conductive pressure-sensitive adhesive sheet is the thickness of the conductive pressure-sensitive adhesive sheet itself that does not include a release liner.

The conductive pressure-sensitive adhesive sheet has a surface resistance value of 1.0 × 10 ⁸ Ω or more, for example, by directly applying the resin composition for forming the resin layer on one surface of the conductive base material and drying it. It can manufacture by passing through the process of forming the resin layer which is and the process of providing a conductive adhesive layer in the other surface side of the said conductive base material.

  Examples of the method of applying the resin composition for forming the resin layer include a method of applying using a comma coater, a method of applying using a gravure coater, and a method of applying using a lip coater. It is done. Among these, as the coating method, it is preferable to employ a method of coating using a gravure coater, and adopting a method of coating with a micro gravure coater forms the resin layer with high accuracy. As a result, it is more preferable for imparting further superior insulating properties.

  After the coating, the resin layer can be directly formed on one surface of the conductive substrate by drying at a temperature of 80 ° C. to 120 ° C.

  The step of providing a conductive pressure-sensitive adhesive layer on the other surface side of the conductive base material is performed by, for example, applying the pressure-sensitive adhesive composition containing conductive particles to one side of the conductive base material and drying it. A process is mentioned.

  In the step of providing a conductive pressure-sensitive adhesive layer on the other surface side of the conductive base material, the pressure-sensitive adhesive composition containing the conductive particles is coated on the surface of a release liner in advance and dried. To form a conductive pressure-sensitive adhesive layer, and then transfer the conductive pressure-sensitive adhesive layer to the other surface side of the conductive base material.

  It is preferable that the conductive thin adhesive sheet produced by any of the above methods is then cured for 48 hours or more in the range of 20 ° C. to 50 ° C. in order to advance the crosslinking reaction of the conductive adhesive layer.

  Examples of the method for applying the conductive adhesive composition to the release liner or the conductive substrate include a method using a comma coater, a method using a gravure coater, and a lip coater. And the method of coating.

  If necessary, a release liner may be laminated on the surface of the conductive pressure-sensitive adhesive layer constituting the conductive thin pressure-sensitive adhesive sheet of the present invention.

  The release liner is not particularly limited. For example, paper such as kraft paper, glassine paper, and high-quality paper, resin films such as polyethylene, polypropylene (OPP, CPP), and polyethylene terephthalate, and the papers and resin films are laminated. Conventionally known such as laminated paper, a monomer in which the surface of the paper is sealed with clay, polyvinyl alcohol, or the like, or one or both surfaces subjected to the sealing treatment is peeled with a silicon-based resin or the like Can be used.

  Examples will be specifically described below.

[Preparation of Insulating Resin Composition A for Forming Resin Layer A]
Polyester polyol having a number average molecular weight of 2,000 which is a reaction product of adipic acid, terephthalic acid and 3-methyl-1,5-pentanediol in a four-flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas introduction tube 192.9 parts by mass, 15.8 parts by mass of 1,4-butanediol and 77.9 parts by mass of isophorone diisocyanate were charged and reacted at 90 ° C. for 15 hours under a nitrogen stream. Next, 11.0 parts by mass of isophorone diamine, 2.4 parts by mass of di-n-butylamine and 700 parts by mass of methyl ethyl ketone were added, and the mixture was reacted at 50 ° C. for 4 hours under a stirring frame, and the resin solid content concentration was 30.0 parts by mass. A polyurethane resin A having a Gardner viscosity U (25 ° C.), an amine value of 0, and a weight average molecular weight of 30,000 was obtained.

  Next, 100 parts by mass of the polyurethane resin A (non-volatile content 30 parts by mass), 13 parts by mass of methyl ethyl ketone, 9 parts by mass of ethyl acetate, 5 parts by mass of isopropyl alcohol, 5 parts by mass of propylene glycol monomethyl ether, Sumika Bayer Urethane Co., Ltd. The insulating resin composition A for forming the resin layer A is prepared by mixing 5 parts by mass of the curing agent “Sumijour N3300” and 40 parts by mass of the diluent “NH-NT DC solvent” manufactured by DIC Graphics. did.

[Preparation of conductive adhesive composition A for forming conductive adhesive layer A]
In a reaction vessel equipped with a condenser, a stirrer, a thermometer and a dropping funnel, 75.0 parts by mass of n-butyl acrylate, 19.0 parts by mass of 2-ethylhexyl acrylate, 3.9 parts by mass of vinyl acetate, 2.0 of acrylic acid After dissolving 0.1 part by mass of 2-hydroxyethyl acrylate and 0.1 part by mass of 2,2′-azobisisobutylnitrile as a polymerization initiator in 100 parts by mass of ethyl acetate and replacing with nitrogen, By polymerizing at 80 ° C. for 12 hours, an ethyl acetate solution of an acrylic polymer having a weight average molecular weight of 600,000 was obtained.

  10 parts by mass of Pencel D-135 (Arakawa Chemical Industries, polymerized rosin pentaerythritol ester, softening point 135 ° C.) with respect to 100 parts by mass of the solid content of the acrylic polymer ethyl acetate solution, Superester A-100 By blending 10 parts by mass (Arakawa Chemical Industries, Ltd., disproportionated rosin glycerin ester, softening point 100 ° C.) and adjusting the solid content concentration of the acrylic polymer to 45 parts by mass using ethyl acetate. An acrylic pressure-sensitive adhesive composition (1) was obtained.

Nickel powder NI123 (d50: 10.3 μm, d85: 22 μm, tap density: 3.5 g / cm) manufactured by Incori Ltd. for 100 parts by weight (45 parts by weight of solid content) of the acrylic pressure-sensitive adhesive composition (1). ³ ) 22.5 parts by mass, cross-linking agent Bernock NC40 (DIC isocyanate cross-linking agent, solid content 40 parts by mass) 2.5 parts by mass, benzotriazole 0.23 parts by mass, solid content with ethyl acetate The concentration was adjusted to 47 parts by mass and mixed for 10 minutes with a dispersion stirrer to obtain a conductive adhesive composition A for forming a conductive adhesive layer A.

Example 1
[Preparation of conductive adhesive sheet]
Using a gravure coater, the insulating resin composition A is dried on an aluminum foil having a thickness of 30 μm (manufactured by Mitsubishi Aluminum Co., Ltd., material: 1N30, tempered: soft) so that the thickness after drying becomes 4 μm. It was coated and dried at 100 ° C. for 2 minutes.
Next, the conductive adhesive composition A was applied to a release film “PET38 × 1 A3” manufactured by Nipper Corporation using a comma coater so that the thickness of the conductive adhesive layer after drying was 25 μm. After coating for 2 minutes in a dryer at 80 ° C., it was bonded to the other surface of the aluminum foil, and then cured at 40 ° C. for 48 hours to obtain a conductive adhesive sheet.

(Example 2)
Using a gravure coater, the insulating resin composition A is dried on an aluminum foil having a thickness of 30 μm (manufactured by Mitsubishi Aluminum Co., Ltd., material: 1N30, tempered: soft) so that the thickness after drying becomes 3 μm. It was coated and dried at 100 ° C. for 2 minutes.

  Next, the conductive adhesive composition A was applied to a release film “PET38 × 1 A3” manufactured by Nipper Corporation using a comma coater so that the thickness of the conductive adhesive layer after drying was 25 μm. After coating for 2 minutes in a dryer at 80 ° C., it was bonded to the other surface of the aluminum foil, and then cured at 40 ° C. for 48 hours to obtain a conductive adhesive sheet.

(Comparative Example 1)
A composition containing an isocyanate-based curing agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name: Coronate L) and a polyester resin (manufactured by Unitika Ltd., product name: UE3220) is gravure so that the thickness becomes 2 μm. After coating with a coater on a 12 μm thick polyester film and drying at 100 ° C. for 2 minutes, on one side of a 30 μm thick aluminum foil (Mitsubishi Aluminum Co., Ltd., material: 1N30, tempered: soft) After pasting, it was cured at 40 ° C. for 48 hours.

  Next, the conductive adhesive composition A was applied to a release film “PET38 × 1 A3” manufactured by Nipper Corporation using a comma coater so that the thickness of the conductive adhesive layer after drying was 25 μm. After coating for 2 minutes in a dryer at 80 ° C., it was bonded to the other surface of the aluminum foil, and then cured at 40 ° C. for 48 hours to obtain a conductive adhesive sheet.

(Comparative Example 2)
The conductive adhesive composition A was coated on a release film “PET38 × 1 A3” manufactured by Nipper Corporation using a comma coater so that the thickness of the conductive adhesive layer after drying was 25 μm. Then, after drying in an oven at 80 ° C. for 2 minutes, it was bonded to one surface of an aluminum foil having a thickness of 30 μm (manufactured by Mitsubishi Aluminum Co., Ltd., material: 1N30, tempered: soft), and then 40 ° C. The conductive adhesive sheet was obtained by curing for 48 hours.

(Evaluation)
The conductive adhesive sheets obtained in Examples and Comparative Examples were evaluated for conductivity, light shielding properties, insulating properties, curling, followability to adherend, and adhesiveness.

[Evaluation method of conductivity]
A conductive adhesive sheet cut to a size of 25 mm width × 100 mm width was affixed to one reciprocating pressure of a 2.0 kg roller between two copper plates so that each application area was 6.25 cm ² , After leaving for 1 hour in an environment of 23 ° C and 50% RH, connect the terminal to the end of the two copper plates (the part that is not bonded together) in the same environment, and use a milliohm meter (NF circuit design) to supply a current of 10μA The resistance value when flowing was measured.
(Evaluation criteria for conductivity)
○: Resistance value is less than 1Ω ×: Resistance value is 1Ω or more

[Insulation evaluation method]
The volume resistance value of the black ink coated surface of the conductive adhesive sheet cut to a size of 100 mm width × 100 mm width was measured using a surface resistance meter (manufactured by Advantest Corporation, model: R8340A).
(Insulation evaluation criteria)
○: Surface resistance value is 1.0 × 10 ¹⁰ Ω or more ×: Surface resistance value is less than 1.0 × 10 ¹⁰ Ω

[Evaluation method of curl characteristics]
The release film was peeled off from the conductive adhesive sheet cut to a size of 20 mm width × 150 mm width, and the curl was visually evaluated.
(Curl characteristic evaluation criteria)
○: Within 1 rotation △: 1-2 rotations ×: 2 rotations or more

[Evaluation method of shape followability]
The release film is peeled off from the conductive adhesive sheet cut into a size of 10 mm width × 20 mm width, and bonded to one side of an aluminum plate bent in a 90 ° direction so as to have a width of 1 mm, and then the other side has a width of 19 mm. Then, the film was bent in a 90 ° direction and bonded, and the surface attached to a width of 1 mm after being left at 85 ° C. for 250 hours was visually evaluated.
(Evaluation criteria for shape following)
○: No peeling Δ: Some peeling occurred ×: The entire surface was peeled off.

Claims (2)

It has a resin layer having a surface resistance value of 1.0 × 10 ⁸ Ω or more directly on one surface of the conductive substrate, and a conductive adhesive layer on the other surface side of the conductive substrate. A conductive pressure-sensitive adhesive sheet comprising: A step of forming a resin layer having a surface resistance value of 1.0 × 10 ⁸ Ω or more by directly applying and drying the resin composition on one surface of the conductive substrate; The manufacturing method of the electroconductive adhesive sheet characterized by having the process of providing an electroconductive adhesive layer in the other surface side of a base material.